Molded articles made from polyolefins tend to have poor scratch and mar resistance. That is, the surface is easily marred or scratched by lightly rubbing with an object such as a fingernail. Articles made from modified polyolefins, for example, propylene polymer materials grafted with one or more vinyl monomers such as styrene and acrylic compounds, also exhibit poor scratch and mar resistance. When rubber is added to these graft copolymers, the scratch and mar resistance of articles made therefrom usually deteriorate.
The scratch and mar resistance of thermoplastic olefins, which are uncrosslinked blends of crystalline olefin polymers and olefin polymer elastomers, was improved by adding a lubricant such as a polysiloxane, either alone or in combination with an aliphatic amide such as erucamide and/or oleamide, as disclosed in European Patent Application 832,925.
There is a need for improving the scratch and mar resistance of a graft copolymer comprising a backbone of a propylene polymer material to which are grafted polymerized vinyl monomers, while still maintaining a good balance of mechanical properties and high surface gloss.